Claudin

Claudin is a family of proteins that are integral to the formation of tight junctions in cellular biology. These proteins are crucial in maintaining the function of biological barriers and cell polarity.

Structure

Claudins are composed of four transmembrane domains, with the N-terminus and the C-terminus in the cytoplasm. They have two extracellular loops, with the first one being larger and more variable.

Function

Claudins play a key role in the formation of tight junctions, which are crucial for the control of paracellular transport and the maintenance of cell polarity. They can form barriers that prevent the passage of solutes through the paracellular pathway, and they can also form pores that allow the selective passage of certain ions.

Clinical significance

Mutations in claudin proteins have been associated with a variety of diseases, including inflammatory bowel disease, deafness, and cancer. In particular, claudin-1 has been found to be a receptor for the hepatitis C virus, and claudin-16 is involved in a form of familial hypomagnesemia.

See also

• Tight junction
• Paracellular transport
• Cell polarity

• Diagram of cellular tight junctions
  Diagram of cellular tight junctions
• Schema of tight junctions
  Schema of tight junctions
• Claudin protein structure
  Claudin protein structure
• Septate junction illustration
  Septate junction illustration
• Claudin in hindgut
  Claudin in hindgut